The present invention relates to improvements in rotary saw blades, and specifically to improvements in multi-directional rotary saw blades, or those capable of cutting circles, curves, grooves, slots, radiuses and plunge cuts.
Conventional rotary saw blades of circular design are not suited for making arcuate, slotted or plunge-type cuts due to the fact that they cannot clear the workpiece and so provide sufficient relief to be maneuverable within the cut. Moreover, and specifically in connection with plunge-type cuts, such conventional blades tend to kick back and grab the material being cut, at times tending to "walk," or proceed without the control of the operator.
A number of multi-directional rotary saw blades addressing such problems encountered with conventional rotary blades are known. Gibb U.S. Pat. No. 2,239,317 discloses an elliptical saw capable of a variety of cuts by essentially chopping wood that is moved laterally or at right angles to the plane of the blade. Toki U.S. Pat. No. 3,712,349, discloses a rhomboidal blade with the teeth on the two cutting edges being arched in opposite directions. Although the Toki blade is capable of being used for multi-directional cutting, it tends to "slap" and kick back from the material, making for a rather rough, choppy and more dangerous cut. Gibb U.S. Pat. No. 3,831,484 discloses a multi-lobed blade having three or more lobes, the peripheral edge contour of which conforms to a portion of the circumference of a circle. Spaced between each lobe is an abreviated sector, the peripheral edge contour of which is parabolic. The primary drawback of such a blade with respect to multi-directional cutting is that it has a very limited depth of cut, that is, the depth of cut at which a portion of the blade can clear the material and so be sufficiently maneuverable to make arcuate and plunge cuts is relatively shallow. More specifically, the depth of cut at which a portion of the Gibb blade clears the material is substantially limited to the radial center line of the circular segment cut out of the circle by the abbreviated sectors. In a typical 71/4 inch diameter blade (the standard size in the marketplace) this depth is less than 1/2 inch.
What is needed thereof is a multi-directional rotary saw blade capable of clearing the workpiece an appropriate number of times per revolution to allow sufficient maneuverability to make arcuate, circular, slotted and plunge cuts, yet cut into the workpiece a sufficient number of times per revolution to be capable of a smooth, even cut and still make a sufficiently deep cut to be useful in commercial construction and home building projects.